Receiver

ABSTRACT

Receiver ( 1 ), in particular an implantable receiver ( 1 ) for transmitting energy to an implant, with a multi-layer circuit board comprising a plurality of electrically conductive layers ( 11 - 16 ), wherein the circuit board comprises an outer coil area and a multi-layer inner area enclosed by the coil area, a coil which is integrally incorporated at least partially in the layers ( 11 - 16 ) of the circuit board in the coil area, wherein the number of the layers ( 11 - 16 ) of the circuit board is smaller within this inner area than in the coil area.

FIELD OF THE INVENTION

The invention relates to a receiver, in particular an implantablereceiver for transmitting energy to an implant, an implantable system,and a method for producing a receiver.

PRIOR ART

The prior art discloses implantable receivers for implants, comprising acoil for receiving energy or signals. In known receivers, a coil made ofcopper enamel wire is soldered onto the printed circuit board andadhesively bonded to the printed circuit board. On account of the sizeand number of the electrical parts, two printed circuit boards aretypically needed which are placed on each other manually and have to beconnected with pins. This entails a large number of assembly steps, andthese steps are also susceptible to error.

U.S. Pat. No. 8,521,303 describes an example of an implantable coilarrangement from the prior art. The planar coil shown there isintegrated in a polymer matrix and can comprise a large number of coillayers. However, the arrangement shown with coil is relatively large.

DISCLOSURE OF THE INVENTION

The object of the invention is to make available a receiver that isimproved in relation to the prior art, and to make available an improvedmethod for producing a receiver. The receiver should in particular bemore compact or less expensive to produce.

The object is achieved, for example, by a receiver according to claim 1or by a method according to the additional independent claim.Developments of the method or of the device are set forth in thedependent claims.

A first aspect concerns a receiver, in particular an implantablereceiver for transmitting energy to an implant, with a multi-layercircuit board comprising a plurality of electrically conductive layers,wherein the circuit board comprises an outer coil area and a multi-layerinner area enclosed by the coil area, a coil which is integrallyincorporated at least partially in the layers of the circuit board inthe coil area, wherein the number of the layers of the circuit board issmaller within this inner area than in the coil area.

A further aspect concerns an implantable system with a receiver, in oneof the typical embodiments described herein, and with anelectromechanical implant.

A further aspect concerns a method for producing a receiver, inparticular an implantable receiver for transmitting energy to an implantcomprising a circuit board, by: producing a multi-layer base membrane ofthe circuit board with a plurality of layers, building up further layerson an upper side and/or an underside of the base membrane, wherein turnsof a coil are integrated at least in some of the further layers in thecoil area, and creating an upper cavity or a lower cavity from thefurther layers in the inner area to the inside of the coil area, byremoving the further layers in the inner area, e.g. by milling orgrinding.

Receivers in some embodiments are implantable, for examplesubcutaneously or close to or on a bone.

One or more insulating sheets are typically provided per conductivelayer. For example, the circuit board structure can be formed byconductive layers alternating with insulating sheets. The lowermostlayer or the uppermost layer can lie exposed or can be covered with afurther insulating sheet.

By means of the larger number of the layers in the coil area, an uppercavity is typically formed, which is delimited by an upper rim. Theupper rim is typically formed at least partially by the further layersin the coil area that are provided above a base membrane. The basemembrane typically comprises the inner area and the outer area. Intypical embodiments, only the base membrane of the circuit board ispresent in the inner area, whereas, in the coil area, further layers canbe formed above or also additionally below the base membrane. Thefurther layers on the underside in the coil area typically form a lowerrim.

Coil turns are typically formed in the coil area. This permits aspace-saving and protected arrangement of the turns in the layers in thecoil area. In typical embodiments, between 3 and 15 turns are providedper layer, in particular between 5 and 10 turns per layer or, inparticular, exactly 7 turns per layer. In typical embodiments, the coilarea comprises three or more layers, for example at least two layers ofthe base membrane or at least two further layers in the coil area. Atleast 3 or at least 4 layers are typically present in the base membraneor in the inner area. At most 6 layers or at most 10 layers aretypically provided in the base membrane or in the inner area. In typicalembodiments, at least 8 further layers or at least 12 further layers arearranged in the coil area. In typical embodiments, at most 16 furtherlayers or at most 25 further layers are present in the coil area.

Typical receivers are suitable for an electro-mechanical implant.Typical electromechanical implants are in particular distractors, whichare suitable for example for the treatment of long tubular bones or ofscoliosis. The receiver is typically designed to provide energy for anelectric drive machine of an active implant, for example a rating of atleast 0.1 Watt or at least 0.5 Watt. Typical embodiments are suitablefor powering active implants, active typically being understood asmeaning that the implant can typically perform a movement or typicallycomprise a drive motor.

In typical methods for producing a receiver, the further layers areapplied both in the inner area and also in the coil area. A typicallayer of the layers of the base membrane or also of the further appliedlayers comprises conductor tracks or typically one conductive sheet perlayer.

In typical methods, by milling out the inner area, an upper rim isformed in the coil area and the upper cavity is formed in the innerarea. Moreover, a lower rim can additionally be formed in the coil area,and the lower cavity can be formed on the underside in the inner area.

Typically, the inner area comprises at most half as many, or less thanhalf as many, layers as the coil area. In this way, an upper cavity iscreated, and optionally also a lower cavity, for receiving electroniccomponents.

In typical embodiments, the coil area, on the upper side of the circuitboard, forms an upper rim around the inner area, wherein electroniccomponents are arranged on the upper side of the circuit board in theinner area. Typically, a maximum height of the electronic components onthe upper side is at most twice, typically at most 1.5 times or at most1.2 times or at most 1.1 times as high as the step between coil area andinner area on the upper side. This step corresponds to the heightbetween the upper side of the base membrane and the top edge of theupper rim. Typically, the limits for the heights apply analogously toelectronic components which are arranged in a lower cavity, present insome embodiments, in relation to the edge of the lower rim. By means ofthe height limits, the components are received in a protectedarrangement and a flat or uniform profile of the receiver is created.

In typical receivers, the coil area or the further layers of the coilarea forms a lower rim on an underside of the circuit board, which lowerrim on the underside encircles a lower cavity in the inner area.

In some embodiments of receivers, electronic components can be enclosedby the base membrane or by the further layers of the coil area, or thebase membrane can be integrated in particular in the layers in the innerarea.

The circuit board is typically formed in one piece. In alternativeembodiments, at least two circuit boards are provided, where an extraone can be provided for the coil. It is possible to use collapsible,adhesively bonded rigid-flex constructions. In the process of producingthe circuit board, this arrangement results in a base membrane in whichfurther layers were built up on the underside. In typical embodiments,only a lower cavity is initially created or no cavity. The upper side ofthe circuit board is thus easier to populate. In addition to inner areaand coil area, the circuit board also has a flexible area. By means ofthis flexible area, after the electronic components have been fitted itis possible for a further coil area to be folded across the circuitboard and adhesively bonded. This embodiment permits a higher inductanceof the coil or also a higher current load. Polyimide can be used asmaterial for the flexible area.

Typical receivers comprise a feedback device which works without radiowaves and which is designed to generate feedback concerning an operatingstate of an implant attached to the receiver. The feedback device istypically arranged in the lower cavity or in the upper cavity. It canalso typically be enclosed by the base membrane or the coil area or canbe integrated in the inner area, in particular in the layers of the basemembrane.

A possible operating state can be the functionality of an implantattached to the receiver or a direction of movement of a drive of animplant attached to the receiver.

Typical receivers comprise a switch for changing the operating state ofthe implant attached to the receiver. Typical switches include: reedcontact, photodiode or electromechanical press switch. Typical switchesare free of electromagnetic radiation and are thus independent of radiowave transmission, for which the coil can typically be used.

In typical embodiments, the upper cavity or the lower cavity is filledwith a resin-catalyst mix. The upper rim or lower rim in the coil areacan in this case serve as a mold. Both cavities are typically filled.

Typical receivers are encapsulated with a biocompatible material, forexample silicone or epoxy resin. In some embodiments, a glass housingwould also be possible, or a ceramic housing in the form that halfshells are bonded or welded to each other.

So as not to damage the biocompatible material, the edges of the printedcircuit board are provided with a radius in some embodiments ofreceivers. In this way, sharp edges can be avoided and implantabilitycan be enhanced.

During the building up of the further layers, the inner area of the basemembrane is typically covered by a protective sheet on at least one ofupper side and underside. Typical protective sheets comprise Teflon, forexample, or are made of Teflon. The protective sheet can be arranged ina prepreg cut out in the inner area or in an insulation sheet cut out inthe inner area.

The circuit board can be produced using known production methods fromprinted circuit board technology for producing multilayer circuit boardswhich permit integration of the coil in the circuit board or also permita selective generation of height levels.

In typical embodiments, after the circuit board has been finished and,if appropriate, the cavity or cavities have been milled out, a solderingpaste is applied in the cavity. This can be done, for example, by jetprinting or dispensing.

Typical methods also include populating the inner area on the upper sidewith electronic components, filling the upper cavity with aresin-catalyst mix, or encapsulating the receiver with a biocompatiblematerial.

Typically, at least 10 layers, typically at least 20 layers or at least24 layers are provided in the coil area. Typical embodiments comprise atmost 100 layers, typically at most 50 layers. Typical coils comprise atleast 50 turns, at least 100 turns, or at least 160 turns. The coiltypically comprises at most 500 turns or at most 200 turns.

Typical advantages of embodiments are a compact structure with muchenhanced functionality or optimized efficiency compared to knownreceivers of active implants. Typical receivers have a height of lessthan 5 mm or of less than 4 mm. The step of the upper rim is typicallyat least 1 mm or at least 2 mm. Typical heights of the lower rim are amaximum of 1 mm or a maximum of 0.5 mm. Typical diameters are at least15 mm or at least 20 mm or at most 30 mm or at most 50 mm. The thicknessof the base membrane is typically at least 5% or at least 7% or at most20% or at most 15% of the overall height of the receiver.

In typical receiver embodiments, more functions can be integrated.Soldering of the coil can be avoided, for example the risk of polarityreversal can be reduced.

Typical embodiments are more robust, since fewer individual parts areused. Moreover, the coil as an integral module of the circuit board ismore protected, and the components inside the cavities are also betterprotected.

For some embodiments, fewer assembly steps are needed than in knownreceivers from the prior art, or the assembly can be done morecost-effectively.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and features of preferred embodiments of theinvention are explained below with reference to the attached drawings,in which:

FIG. 1 is a schematic sectional view of an embodiment of the invention;

FIG. 2 shows a further embodiment in a perspective schematic view; and

FIG. 3 shows the sequence of a method according to the invention.

DESCRIPTION OF PREFERRED ILLUSTRATIVE EMBODIMENTS

Typical embodiments are described below with reference to the figures.The invention is not limited to the illustrative embodiments. Instead,the scope of the invention is defined by the claims.

FIG. 1 shows a receiver 1, which can be part of an implant system thatcan comprise an electromechanical implant (not shown in the figures)attachable to the receiver 1.

The receiver 1 is implantable and suitable for transmitting energy tothe implant. For this purpose, the receiver 1 comprises a coil, which issuitable for transmitting or receiving energy sufficient to power anelectromechanical drive of an implant, for example of an intramedullarynail, as is shown in DE 10 2011 053 638 A1 for example, or of ascoliosis treatment unit, as is shown in DE 10 2010 047 738 A1 forexample.

The receiver 1 is suitable for transmitting a constant rating of atleast 1W to an active or mechatronic implant.

The receiver 1 comprises a multi-layer circuit board, which comprises abase membrane 3 extending horizontally across the entire cross sectionof the circuit board. The base membrane comprises four layers 11-14,which are designed as electrically conductive, structured copper layers.

In an outer coil area, the circuit board has fifteen upper furtherlayers 15 forming an upper rim 17, and three lower further layers 16forming a lower rim 18. For the sake of clarity, not all of the furtherlayers are provided with reference signs.

The rims 17 and 18 each extend circumferentially around an inner area inwhich only the four layers 11-14 of the base membrane are present.

Prepregs are arranged as insulation sheets between all of the layers11-16, wherein the outermost layers 11 and 14 in the inner area lieexposed such that, on an upper side of the base membrane (layer 14) andon an underside of the base membrane (layer 11), it is possible toarrange electronic components, which are shown by way of example on theupper side by reference signs 21, or contacts 22.

In the coil area, the layers 11-16, i.e. the layers 11-14 of the basemembrane and the upper and lower further layers 15 and 16, form coilturns of the coil. Seven turns (shown only schematically in FIG. 1) arearranged on each layer 11-16. In this way, the coil is incorporatedintegrally in the layers of the circuit board in the coil area.

In some embodiments, embedded parts can be integrated in the basemembrane in the inner area. Moreover, packaged or unpackaged components,ICs, transistors or resistors can be arranged there. In particular, testpoints can be provided on the underside or on the upper side in order tomake it easier to test the receiver before it is encapsulated withsilicone. Furthermore, receivers in some embodiments can be providedwith a ferrite sleeve around the coil area or a paste in order toimprove the efficiency of the coil.

In typical embodiments, the circuit board comprises printed circuitboard materials known from the prior art, for example FR4 or polyimide.

An upper cavity is formed in the inside of the upper rim 17. A lowercavity is formed in the inside of the lower rim 18. The electroniccomponents 21 of the embodiment shown do not protrude above the upperrim 17. This means that the electronic components 21 have an overallheight lower than the height of the top of the rim 17 above the surfaceof the upper side of the base membrane.

In some embodiments, the height of the rim can be defined as the heightbetween the exposed layer, or uppermost/lowermost layer, of the innerarea and the top of the rim.

A piezo buzzer 26 arranged in the lower cavity protrudes past the lowerrim 18 only by 10% of the height of the lower rim beyond the exposedlayer 11 of the underside of the base membrane. A compact structure isobtained in this way.

A lug 30, formed from the layers 11-14 of the base membrane and from thelower additional 16, is provided on one side. The lug 30 can be usedwith the exposed layer 14 for contacts, for example for attachment ofthe implant.

The cavities formed by the rims 17 and 18 are filled with aresin-catalyst mix. The entire receiver 1 is encapsulated with silicone32, such that it is biocompatible.

FIG. 2 shows a further embodiment of a receiver 1 for a mechatronicimplant. The cavities of the receiver 1 in FIG. 2 are not yet filledwith resin-catalyst mix, and the silicone layer is also missing.

The perspective view in FIG. 2 shows clearly how the upper rim 17encircles an inner area in which electronic components 21 can bearranged and protected.

In typical embodiments, electronic components are arranged in the innerarea on the upper side or underside, or both, of the base membrane. Thearrangement offers good protection against mechanical influences.

FIG. 3 shows a typical method for producing a receiver. The methodstarts in block 110, where a four-layer base membrane is produced.Structured layers of copper (cores) and insulation sheets (prepregs) arethen alternately applied and press-molded.

The base membrane is composed of four copper sheets (the layers) andthree insulation sheets, which are structured, bored and electroplated.In the finished receiver, the upper copper sheet forms the layer on theupper side of the base membrane in the upper cavity, on which layer thecomponents are fitted. In the finished product, the test points arelocated on the lowermost layer of the base membrane.

In a block 120, a prepreg milled out in the inner area, i.e. in the areaof the cavities, is placed on the upper side and the underside of thebase membrane.

In a block 130, Teflon disks are inserted into these milled-out areas.In contrast to the insulating material, these disks do not connect tothe copper sheet of the outermost layers of the base membrane.

In a block 140, further layers and prepregs are applied as insulatingmaterial to the upper side and to the underside of the base membrane.The respectively outermost sheet is insulating material.

In a block 150, a contour is milled in the resulting unpopulated circuitboard, the milling being carried out to the depth of the Teflon disk.This results in a cavity on the upper side and a cavity on the undersideof the unpopulated circuit board.

In a block 160, the Teflon disks are removed from the unpopulatedcircuit board.

In a block 170, the surfaces of the cavities are finished with a thinsheet of nickel (e.g. 3-10 nm) and a thinner sheet of gold (ca. 0.5-3nm).

In a block 180, a soldering paste is applied to the finished surfaces ofthe cavities, e.g. by jet printing or dispensing.

In a block 190, the footprints, i.e. landing areas provided forcomponents, in the cavities are populated with electronic components.

In a block 200, the soldering tin under the feet of the electroniccomponents melts in the soldering furnace, typically with a vapor phase,in order to obtain uniform heat distribution, and the structural partsconnect to the circuit board.

In a block 210, the cavities are filled with a resin-catalyst mix untilthe cavities are at least substantially full to the top. Typically, nopotting mold is used for this purpose. The potting is typically carriedout without a potting mold.

In a block 220, the circuit board thus obtained is encapsulated withsilicone in order to make the receiver with the circuit boardbiocompatible. With that, the method shown in FIG. 3 is completed.

1. Implantable receiver for transmitting energy to an implant, with amulti-layer circuit board comprising a plurality of electricallyconductive layers, wherein the circuit board comprises an outer coilarea and a multi-layer inner area enclosed by the coil area, a coilwhich is integrally incorporated at least partially in the layers of thecircuit board in the coil area, wherein the number of the layers of thecircuit board is smaller within this inner area than in the coil area.2. Receiver according to claim 1, wherein the inner area comprises atmost half as many layers as the coil area.
 3. Receiver according toclaim 1, wherein the coil area, on an upper side of the circuit board,forms an upper rim around the inner area, and wherein electroniccomponents are arranged on the upper side of the circuit board in theinner area.
 4. Receiver according to claim 1, wherein the coil areaforms a lower rim on an underside of the circuit board, which lower rimon the underside encircles a lower cavity in the inner area.
 5. Receiveraccording to claim 1, wherein the circuit board is formed in one piece.6. Receiver according to claim 1, with a feedback device which workswithout radio waves and which is designed to generate feedbackconcerning an operating state of an implant attached to the receiver. 7.Receiver according to claim 1, wherein the cavity or the cavities arefilled and/or the receiver is encapsulated with a biocompatiblematerial.
 8. Implantable system with an electromechanical implant and animplantable receiver for transmitting energy to the implant, with amulti-layer circuit board comprising a plurality of electricallyconductive layers, wherein the circuit board comprises an outer coilarea and a multi-layer inner area enclosed by the coil area, a coilwhich is integrally intergrated at least partially in the layers of thecircuit board in the coil area, wherein the number of the layers of thecircuit board is smaller within this inner area than in the coil area.9. Method for producing an implantable receiver for transmitting energyto an implant and comprising a circuit board, by: producing amulti-layer base membrane of the circuit board with a plurality oflayers; building up further layers on an upper side and/or an undersideof the base membrane; wherein turns of a coil are integrated at least insome of the further layers in a coil area; creating an upper cavity or alower cavity in the inner area to the inside of the coil area, byremoving the further layers in the inner area.
 10. Method according toclaim 9, wherein the inner area of the base membrane is covered, on atleast one of upper side and underside, by a protective layer during thebuilding up of the further layers.
 11. Method according to claim 9,further comprising: populating the inner area with electronic componentson the upper side, and filling the upper cavity with a resin-catalystmix.
 12. Method according to claim 9, further comprising: encapsulatingthe receiver with a biocompatible material.